This invention relates to a mandibular advancement device that has application in the treatment of orthodontic conditions, snoring, obstructive sleep apnea (OSA) and certain temporomandibular joint disorders.
It is generally thought that snoring and OSA occur when there is at least partial occlusion of the airway and that the tongue is involved in this. Snoring and OSA commonly occur during sleep. Mandibular advancement devices advance the lower jaw carrying the tongue forward thereby reducing the likelihood of the tongue impacting on the airway.
Numerous forms of mandibular advancement device are known. One example can be found in International Publication No. WO 95/19746 (PCT/CA95/00009), in the name of The University of British Columbia, which discloses a mandible repositioning appliance formed by an upper bite block (16) and a lower bite block (18) interconnected by an extendible connector (26). The arms (40,42) that join the lower and upper bite blocks extend from a location proximate the lower incisors rearwardly at an inclined angle, to be anchored in the roof of the mouth. There is thought to be a disadvantage with this arrangement, in that the connector (26) and attachment arms (30,32,40,42) intrude excessively into the oral cavity, and the resulting interference may limit efficacy and/or it may be progressively less effective with increasing mouth opening, or it may not permit jaw opening. It is also thought that the bulk of the connectors (50 and 52) embedded in the lower bite block and the limitation to jaw closure may limit compliance.
It is useful at this point to make reference to a terminology relating to mandibular movement that is adopted in this specification, and particularly the discussion of xe2x80x9cBorder Movementsxe2x80x9d presented in the text Handbook of Orthodontics for the Student and General Practitioner, by Dr Robert E Moyers, published by Year Book Medical Publishers Incorporated of 35 Fast Wacker Drive, Chicago, Ill., U.S.A., Third Edition, Section 1, Part D, pages 148-151. As shown in FIG. V-10, sagittal mandibular movement occurs within a range limited by the border movements, broadly characterised by the most protruded path of opening and closure, the maximal open position of the mandible, the occlusal positions and the most retarded path of closure. In this sense, a reference herein to mandibular advancement represents locating of the mandible so that it functions in the protruded range from the reflex or habital path of closure (occurring between the intercuspal occlusal position and the maximum open position) to the protrusive border path.
It is an object of the present invention to provide a mandibular advancement device that provides advancement of the lower jaw, and permits freedom of sagittal jaw movement (ie. jaw opening) while retaining advancement within a range protruded from the reflex or habitual path of closure.
It is a further, preferred object for embodiments of the invention to provide a mandibular advancement device which can permit closure to the protruded occusal position.
It is a further, preferred object for embodiments of the invention to provide a mandibular advancement device which can be adjustable to give a variable extent of advancement of the lower jaw.
It is a yet further, preferred object for embodiments of the invention to provide a mandibular advancement device having minimal interference with the tongue, the oral airway, mouth seal and the fundamental tongue space.
The invention provides a mandibular advancement device for the treatment of Obstructive Sleep Apnea and/or snoring, comprising:
at least one lower engagement member having an attachment structure adapted to be releasably attachable to at least a portion of the lower jaw and an engagement surface extending upwardly from said attachment structure; and
at least one upper engagement member having an attachment structure adapted to be releasably attachable to at least a portion of the upper jaw and an engagement surface extending downwardly from said attachment structure; and
wherein, when fitted to a patient, the lower and upper engagement surfaces are adapted to engage at a location lying in an area beside and close to the posterior teeth in a manner to cause advancement of the lower jaw from the reflex path of opening and to maintain the engagement and advancement, while permitting sagittal movement, up to the normal range of jaw opening extending from an advanced occluding position.
In one particular preferred form, there are two lower engagement members and two corresponding upper engagement members. The upper and lower engagement surfaces are located on either the buccal sides or the lingual sides of the posterior teeth.
In one particular embodiment the upper and lower engagement surfaces can be essentially edge-like. The antagonist surfaces can be arranged so that their engagement is generally arcuate with the protrusive border path over the normal range of jaw opening. The engagement surfaces can be relatively positionally adjustable, for example by use of a screw extension device, to give a variable extent of advancement of the lower jaw in the horizontal plane. The shape of the engagement surfaces can be chosen to provide a variable extent of advancement over the range of opening to depart from the arc of the protrusive border path.
In another form there is a single upper attachment structure and a single lower attachment structure that respectively are in the form of plates, with two engagement surfaces extending therefrom. There can be an elastic lining arranged to closely adapt to the respective dentition.
Advantageously, the respective lower jaw plate and upper jaw plate are shaped to closely adapt to the lower and upper dentition.
The advancement device can be fitted when the lower jaw is at the maximum open position.
In another form, there is provided a mandibular advancement device as defined above, except either the upper or lower engagement member are replaced physically and in function by the buccal surface of the upper dentition or the lingual surface of the lower dentition, respectively.
The invention further discloses a kit of parts, or spare parts comprising a lower engagement member and/or an upper engagement member as those members are defined above.
The invention further discloses a method that has application in the treatment of obstructive sleep apnea and/or snoring, comprising the steps of:
releasably fitting a mandibular advantage device, having upper and lower jaw components, to a patient, the components engaging at a location in an area beside and close to the posterior teeth and causing advancement of the lower jaw from the reflex path of opening; and
maintaining engagement and advancement, while permitting sagittal movement, up to the normal range of jaw opening extending from an advanced occluding position.
Embodiments of the invention offer advantages over prior art arrangements. Firstly, lower jaw advancement is achieved both when the jaw is closed and over a range of jaw openings, meaning that the therapeutic affect can be achieved in the presence of jaw closure and opening. Also, advancement is retained for all extents of mouth opening, tending to ensure treatment efficacy.
A corollary is that a patient is able to have an unrestricted range of jaw movement from open to almost closed. Because the patient is able to perform these movements without restriction, this may lead to increased compliance with the treatment. Freedom of opening of the lower jaw also allows the user to yawn and perform other functions such a licking of the lips.
Further advantages are that the location of the engagement members means that speech and aethetics are only minimally affected.
Patients can be intolerant of artificial bite opening. Thus the zero or minimal bite opening in the protruded occlusal position may result in improved tolerance and compliance with treatment. With zero or minimal bite opening the important function of swallowing is facilitated. The user also is more likely to have upper to lower lip seal reducing mouth and throat desiccation and perhaps helping in stabilisation of the mandible and tongue. These effects may result in improved efficacy tolerance and compliance with treatment.
The positioning of the engagement surfaces close to and beside the posterior teeth is such as to not impact on the airway, or the active area of the tongue significantly. This is important in promoting patient compliance with the treatment, as any impingement on the oral route of respiration can increase the velocity and turbulence of orally inspired air resulting in lowered air temperature and oral dessication, and can be an actual or perceived impediment to oral respiration. Also, artificial bite opening or encroachment on oral tongue space may cause the tongue to encroach on the pharyngeal airway. Furthermore, the positioning of the engagement members beside the upper and lower posterior teeth allows the engagement surfaces to be sufficiently long to ensure protrusion over any degree of jaw opening likely to occur, and there is no limitation to jaw closure.